Date: Mon, 2 Nov 2015 10:53:35 +0100
From: Michal Hocko <mhocko@kernel.org>
To: "Huang, Ying" <ying.huang@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>, lkp@01.org,
        LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Rik van Riel <riel@redhat.com>, Vitaly Wool <vitalywool@gmail.com>,
        David Rientjes <rientjes@google.com>, Christoph Lameter <cl@linux.com>,
        Johannes Weiner <hannes@cmpxchg.org>, Vlastimil Babka <vbabka@suse.cz>,
        Stephen Rothwell <sfr@canb.auug.org.au>
Subject: Re: [lkp] [mm, page_alloc] 43993977ba: +88% OOM possibility
Message-ID: <20151102095334.GE630@dhcp22.suse.cz>
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 <20151030103830.GJ18429@dhcp22.suse.cz>
 <87poztfgsa.fsf@yhuang-dev.intel.com>
 <20151102074542.GC630@dhcp22.suse.cz>
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On Mon 02-11-15 16:55:15, Huang, Ying wrote:
> Michal Hocko <mhocko@kernel.org> writes:
[...]
> > It would be interesting to see all the page allocation failure warnings
> > (if they are different). Maybe other callers have relied on GFP_ATOMIC
> > and access to memory reserves. The above path is not this case though.
> 
> I take a look at all dmesgs, and found the backtrace for page allocation
> failure is same for all.  Is it possible that this commit cause more
> memory were allocated or kept in memory so that more OOM were triggered?

I can imagine that some of the callers were not converted properly or
missed and a lack of __GFP_KSWAPD_RECLAIM could indeed cause a later
kswapd kick off. I am staring into the commit but nothing has jumped at
me yet. Could you collect /proc/vmstat (snapshot every 1s) on both good
and bad kernels. I expect the later would see a less scanning by kswapd.
-- 
Michal Hocko
SUSE Labs
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